Linux i/o tweaking

Roy Sigurd Karlsbakk
2001-11-15T16:13:26Z

Hi all

After three days at Compaq's lab in Oslo, testing their medium-level
servers and storage systems with Linux, I've come to some sort of
conclusions, although these may be wrong. I also have come over a few
problems that I couln't find a good solution to.

* When running RAID from a Compaq Smart 5302/64 controller, software
RAID-5 is (slightly - ~15%) faster (on JBOD - each disk is configured as
a RAID-0 device with max - 256kB - stripe size) than the
hardware/controller based RAID-5. Both CPUs (1266MHz/512kB cache) are
maxed out by reading from software RAID-5 (???), giving me >= 107MB/s on
two SCSI-3 buses with six disks on each bus.

* Even though I can get up to 25 MB/s from each disk, I can't get more
than 107 MB/s on the whole bunch (12 drives). It doesn't help much to do
RAID-0 either. Don't understand anything ...

Thanks for all help.

roy